Polygonum arifolium L.
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Authority
Park, Chong-Wook. 1988. Taxonomy of Polygonum Section Echinocaulon (Polygonaceae). Mem. New York Bot. Gard. 47: 1-88.
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Family
Polygonaceae
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Scientific Name
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Description
Species Description - Scandent annual herb arising from a fibrous root system, 0.2-1.5 m tall; stem branched, light green, often reddish-purple at maturity, glabrous, angled, armed with recurved prickles along the angles, often producing roots at lower nodes; prickles stout, ca. 1 mm long. Middle and lower leaves long-petioled, triangular to broadly elliptic, 6.5-13 cm long, 6-10.8 cm wide, acuminate at the apex, broadly hastate with two widely divergent acuminate triangular lobes at the base, prickly at the margin; upper leaves small, short-petioled, usually lanceolate, 3.5-6 cm long, 1-2 cm wide, cordate or somewhat sagittate at the base; upper surfaces dark green to green, moderately to densely pubescent with appressed simple multiseriate hairs to 1 mm long and with stellate hairs, rarely glabrous; stellate hairs scattered, sessile, 4- to 5-rayed; lower surfaces light green, covered with 4- to 6-rayed sessile stellate hairs, rarely glabrous; midveins and major veins beneath bearing prickles; prickles 1-1.5 mm long; petioles light green, retrorsely prickly. Ocreae scarious, 0.8-1.5 cm long, oblique, usually glabrous but often with bristlelike hairs, bristly-ciliate at upper margin, bearing short prickles at the base. Inflorescences terminal or in the axils of upper leaves, elongate, often branched, 2-10 cm long, often associated with reduced leaves, usually densely pubescent with glandular hairs and 4- to 5-rayed sessile stellate hairs; glandular hairs stalked, 0.5-0.7 mm long; each inflorescence branch terminated by a loose interrupted panicle or a headlike cluster of 3-8 flower fascicles. Flower fascicles 2- to 4-flowered, usually widely spaced; bracts elliptic, hispid, 5-8 mm long, with elongate acuminate apex; bracteoles broadly elliptic, 2-3 mm long, sparsely stellate-pubescent toward the apex; pedicels short, 2-3 mm long, glabrous, almost included in bracteoles; perianth 4-parted, 5-6 mm long, pink or red, often whitish-green at the base; tepals broadly elliptic, not becoming fleshy; stamens 6(-8), inserted at the base of perianth in two whorls; inner stamens two, ca. 1.3 mm long; outer stamens four, ca. 1 mm long; style one, 2-cleft up to middle, ca. 1 mm long, included; stigmas two. Achenes biconvex, acute at the apex, dark brown to black, smooth, shiny, 4-6 mm long.
Distribution and Ecology - Distribution. In moist situations, usually in shade; predominantly in margins of swamps, ponds, and tidal marshes along rivers, occasionally in shaded thickets along streams and wet ravines in forests; in eastern North America, from Prince Edward Island to Georgia, and from the east coast westward to Minnesota and Kentucky. Also, known from one isolated locality in Washington State (Klickitat Co., Husum, Mt. Paddo) (Fig. 18).
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Discussion
6. Polygonum arifolium L., Sp. pl. 364. 1753. Tracaulon arifolium (L.) Raf., Fl. tellur. 3: 13. 1837. Truellum arifolium (L.) Sojak, Preslia 46: 145. 1974. Persicaria arifolia (L.) Haraldson, Symb. Bot. Upsal. 22: 72. 1978. Type. LINN 510.34 [lectotype (microfiche at NY!), designated by Reveal, J. Linn. Soc., Bot. 92: 168, 1986; without locality, date, and collector’s name]. Polygonum sagittatum var. pubescens Keller, Bull. Soc. Roy. Bot. Belgique, Part 2. 30: 45. 1891. Polygonum arifolium var. pubescens (Keller) Fern., Rhodora 48: 53. 1946. Type. U.S.A. New York: Wet grounds nr. Troy, in 1870, Puissant s.n. (not seen; see Fernald, Rhodora 48: 53. 1946). Polygonum arifolium var. lentiforme Fern. & Griscom, Rhodora 37: 167. 1935. Type. U.S.A. Massachusetts: Southwick, swamp along Great Brook, 9 Sep 1914, Seymour 251 (holotype, GH!; see Park, Brittonia 38: 399. 1986). Polygonum arifolium is highly variable in pubescence. In its southern range, which comprises Virginia, North Carolina, South Carolina, and Georgia, the species consistently displays moderately to densely pubescent ocreae. In addition, it tends to be more pubescent on both surfaces of the leaves. However, most populations from the northern part of its range, from Canada to New York, have completely glabrous ocreae. Also, foliar pubescence is far more variable, from densely pubescent on both surfaces to completely glabrous. In New Jersey and Maryland, where interpopulational variation is high, both these forms are found. However, populations of these forms did not show any significant qualitative differences in flavonoid chemistry (Park, 1987).